Sub- and super-critical carbon dioxide flow behavior in naturally fractured black coal: An experimental study

► Permeability of super-critical CO2 is significantly lower than sub-critical CO2. ► There is a higher viscosity and swelling associated with super-critical CO2. ► Super critical CO2 shows higher decline of permeability with injecting pressure. ► Swelling may cause CO2 permeability to increase for higher injecting pressures. ► N2 has the potential to reverse some swelling effects due to CO2 adsorption.